Recent work with both avian and mammalian species has demonstrated that the sequential onset of functioning of the sensory systems and the resulting reduction or enhancement of competition between the modalities can serve as an important source of perceptual organization in early development. For example, evidence from precocial animal infants indicates that premature stimulation of a later developing sensory system alters the normal functioning of earlier developing sensory systems However, the mechanisms underlying this dynamic nature of perinatal sensory/perceptual organization have not been explicitly studied. The overall aim of the experiments in this three year study is to assess how sensory systems and their respective stimulation histories influence one another during late prenatal and early postnatal development. Seven related studies, utilizing precocial avian embryos and hatchlings, will examine (a) how premature visual experience affects postnatal auditory and visual functioning, (b) how enhanced auditory prenatal auditory experience affects postnatal auditory and visual functioning, and (c) whether enhanced prenatal auditory experience affects prenatal and postnatal taste sensitivity. Results will add to our knowledge of the nature of early intersensory interaction and will provide a source of comparative data for the growing body of research concerned with intersensory processes in the precocial human infant.